Many devices combust material to create a flame. For example, a fireplace is an efficient method for providing warmth and creating the appeal of a fire. A gas fireplace combusts a gas, usually LP or natural gas or a mixture thereof, combined with air to create a gas flame.
Factory-built fireplace assemblies have long been available as both free-standing and wall recessed units. One popular form of a fireplace functions as a room heater and comprises a combustion chamber surrounded by an enclosure providing a passageway for circulating room air over the combustion chamber. Heated air may thereby be circulated into the room either by gravity or by use of a blower system. This type of fireplace is preferably fired with natural or LP gas and has ceramic or cement artificial logs simulating the appearance of a wood burning fireplace while offering the advantage of efficiently converting the natural or LP gas to room heat.
A common design of a gas-fired fireplace includes a combustion chamber that is fabricated as a sealed enclosure. Some of these sealed enclosures fireplaces are vented by a concentric pipe arrangement in which flue gases are exhausted through a central pipe while intake air is drawn into the combustion chamber through an annular space defined by an outer larger diameter pipe. Such a direct-vent fireplace construction has become popular because the cooling effect on the central exhaust pipe by the intake air allows the fireplace to be vented without costly masonry chimney construction.
In a standard design of the gas-fired fireplace, the combustion chamber is sealed at its front face by a glass panel. The glass panel serves to enclose the combustion chamber while allowing the fire to be viewed by the occupants of the room. However, a failure in the ignition system of the fireplace could cause excess accumulation of gas within the combustion chamber which, if ignited, could in turn cause a combustion chamber explosion. Such an explosion could pose a safety hazard to the room occupants if the glass fireplace front were to shatter. Accordingly, it is common in fireplace design to incorporate explosion relief panels in the top of the metal enclosure that forms the combustion chamber. These panels are essentially designed to blow out under the pressure of an explosion and relieve the combustion chamber pressure without breaking the glass front.
A disadvantage of present fireplace construction using explosion relief panels in the combustion chamber is that in the event the panels are blown out by an explosion, it is a very labor-intensive job to repair the fireplace. Particularly, in typical cases in which the fireplace is a wall-recessed unit, the entire fireplace must be disassembled and removed from the wall to gain access to the relief panels. Generally, another disadvantage of common fireplace construction is that the frontal glass panel is mechanically secured to the fireplace enclosure by screws and other hardware making it time consuming to gain access to the interior of the enclosure in the event that maintenance of the fireplace needs to be performed.
Another way that pressure relief has been provided is by using a spring latch mechanism to allow a forwardly facing glass panel to pivotably open to relieve the pressure in the chamber. This type of arrangement is discussed in detail in our U.S. Pat. No. 5,613,487, which is incorporated by reference herein. This system provides the pressure relief mechanism at the front of the fireplace. Additional safety measures, however, are always desired in order to increase the safety of existing and future fireplace systems.
Accordingly, it is desirable to provide a fireplace assembly with an improved safety response in the event of a gas explosion.